The invention relates to the field of medicine. More specifically, the invention relates to the field of diagnostics and radiotherapy.
Reliable, detailed diagnostics is often a key prerequisite for efficient treatment of a disorder. Especially disorders which display a significant different pattern in each individual patient involve the need for very careful and accurate diagnosis. Such disorders for instance comprise tumour-related diseases. If a patient has been found to suffer from a tumour, it is important to obtain reliable insight into the status of the disease. For instance the growth and position of the tumour should be established, and it should be determined whether there are metastases in other parts of the body, etc. Additionally, adequate information about targeting of a drug to a tumour can increase a treatment efficacy.
Many scanning techniques are known, such as magnetic resonance imaging (MRI) which provide information of the internal status of an individual. A contrast agent is often used in order to be capable of obtaining a scanning image. For instance ferrite particles and gadolinium-DTPA (diethylaminetriaminepentaacetic acid) complexes are often used in contrast agents for MR scanning. This way, a good impression can be obtained of internal disorders, like the presence of (a) tumour(s).
After diagnosis, a treatment is often started involving administration of a pharmaceutical composition to a patient. It is often important to monitor the status of a patient during treatment as well. For instance the course of a treatment and targeting of a drug can be monitored, as well as possible side effects which may imply a need for terminating, or temporarily interrupting, a certain treatment.
Sometimes local treatment in only a specific part of the body is preferred. For instance, tumour growth can sometimes be counteracted by internal radiotherapy comprising administration of radioactive particles to an individual. If said radioactive particles accumulate inside and/or around the tumour, specific local treatment is possible. However, to prevent radiation-induced gastritis and/or radiation pneumonitis, patients with significant shunting to the gastroduodenum and the lungs must be excluded from therapy. Therefore, the exact distribution of the radioactive particles is determined by firstly administering a tracer dose comprising said radioactive particles. This involves extra exposure of radioactivity, both for the patient and the medical staff, which is unwanted. Furthermore, some kind of radioactive particles, such as radioactive yttrium, can hardly be detected with a gamma camera. If such yttrium particles are to be used for therapy, other radioactive particles (for example: technetium labelled albumin particles) which can be detected with a gamma camera and which are expected to target and distribute approximately similar as said yttrium particles are administered before treatment. A distribution of said other radioactive particles is then determined. Because said distribution of said other radioactive particles is considered to be approximately similar to a distribution of yttrium, it can approximately be estimated whether significant shunting of yttrium to the gastroduodenum and/or the lungs will occur.
It is thus very complicated to determine how such particles should be used, and what the distribution pattern will be. These problems cannot be solved with current non-radioactive scanning techniques, because the distribution of MRI contrast agents is not the same as the distribution of radioactive therapeutic compounds.
After the radioactive therapeutic compound has become non- (or barely) radioactive, its distribution cannot be followed anymore. This is inconvenient, because it would be desirable to monitor how said compound is removed from the body. Information about the biodistribution of said compound gives an indication about the course of a disease and/or treatment, and about the status of a patient.